Leucoagaricus aurantiovergens A. Gennari & Migl. Riv. Micol.

Forin, Niccolò, Tatti, Alessia, Vizzini, Alfredo, Coppola, Alessandra & Migliozzi, Vincenzo, 2022, Leucoagaricus cupresseoides (Agaricaceae), a new species in sect. Piloselli and L. aurantiovergens and L. pseudopilatianus redescribed from Italy, Phytotaxa 536 (2), pp. 126-140 : 134-136

Leucoagaricus aurantiovergens A. Gennari & Migl. Riv. Micol. 4: 291 (1999) [1998] Figs. 5–6

= Leucoagaricus paracupresseus Salom, Siquier, Planas & Espinosa, Index Fungorum 485: 1 (2021)

= Leucoagaricus pseudopilatianus var. roseodiffractus Migl. & Resta, Micol. Veg. Medit. 15: 129 (2001)

The description is based on the Italian collections, the isotype of L. aurantiovergens , and the holotype of L. pseudopilatianus var. roseodiffractus ( Figs. 5–6 ).

Description:— Pileus medium-sized, 22–92 mm diam, convex or plano-convex, sometimes slightly centrally depressed, without an umbo or velar remnants; surface finely squamulose, brown, reddish brown, dark vinaceous red, with some grey-brown pigmentation, turning vinaceous brown after bruising. Lamellae free, creamy white, turning orange and purple-red after bruising; crowded, sometimes interspersed with white or rose-white lamellulae, edges entire, concolorous with faces, and sterile. Stipe 50–160 × (8) 10–16 mm, hollow, cylindrical, white, with a basal bulb 18–30 mm broad, turning orange, red and brown after bruising, fibrillose. Annulus simple, located at the middle or at the lower half of the stipe, persistent, ascending or descending, white with brown margin, consisting of cylindrical, ramified elements, 40–100 × 7–14 μm. Context white. Smell not distinctive, fungoid. Pileus , lamellae and stipe turn brown when dried.

Basidiospores (6–) 7– 7.7 –8.5 (–11) × (4–) 4.5– 5 –5.5 (–6.7) μm, Q= (1.1–) 1.4– 1.6 –1.7 (–2.1) [400, 8, 8], hyaline, smooth, with short ogival or sub-papillate hilar appendage, without a germ pore, subglobose to ellipsoid, sometimes sub-amygdaliform in side-view, dextrinoid, metachromatic in Cresyl Blue. Basidia 26–32 × 9–13 μm, four-spored, clavate. Hymenophoral trama regular, composed of colorless, cylindrical, up to 16 μm wide hyphae. Cheilocystidia (25) 30–45 (60) × (8) 10–15 (17) μm, abundant, fasciculate, clavate-cylindrical to clavate, rarely lageniform, with rounded apex, not pedicellate, hyaline, with brownish intracellular pigments and necropigments in dried specimens treated with ammonia. Pleurocystidia not observed. Pileus covering trichodermal, consisting of terminal elements (70) 80–200 (290) × (7) 9–19 (21) μm, cylindrical with rounded apex, with brownish pigments both parietal and intracellular, presence of brownish necropigments in dried specimens with ammonia; preterminal elements cylindrical, pigmented, 4–7 μm wide. Clamp connections absent.

Macrochemical reactions:—Lamellae, pileus and stipe surfaces turn green when treated with NH 4 OH.

Habitat and distribution:—Terrestrial, growing in small groups mainly in the Mediterranean area. It has been found under Cupressaceae in France; in Italy under Cupressus sempervirens , Ficus sp. , Phytolacca dioica , Pistacia lentiscus and Quercus ilex ; in Spain (Majorca) associated with Pinus halepensis , Juniperus phoenicea , Pistacia lentiscus and Ephedra fragilis .

Material examined:— ITALY. Grosseto, Ansedonia , under Cupressus sempervirens and Pistacia lentiscus , near Quercus ilex and Pinus pinea , about 100 m from the sea, 14 January 1996, A. Gennari, PAD H0061557, isotype of Leucoagaricus aurantiovergens (holotype MCVE 74 ), GenBank accession OK235666 (nrITS); ITALY. Rome, Fiumicino , Macchia Grande di Focene-Macchia dello Stagneto , under Quercus ilex , 13 November 1997, V. Migliozzi, TR MV36/97, holotype of Leucoagaricus pseudopilatianus var. roseodiffractus, GenBank accession OK235670 (nrITS) ; ITALY. Sardinia, Cagliari, Botanical Garden, under Pistacia lentiscus , 07 December 2016, A. Tatti, CAG P.12-9/8.39a, GenBank accession OM327663 (nrITS); ITALY. Sardinia, Cagliari, Botanical Garden, under Ficus sp. and Phytolacca dioica , 07 December 2017, A. Tatti, CAG P.12-9/8.39b, GenBank accession OM327664 (nrITS); ITALY. Sardinia, Cagliari, Botanical Garden, under Ficus sp. and Phytolacca dioica , 05 January 2018, A. Tatti, CAG P.12-9/8.39c, GenBank accession OM327665 (nrITS); ITALY. Rome, San Giovanni, under Cupressus sempervirens , 14 November 2018, V. Migliozzi, MVBB34, GenBank accession OK235665 (nrITS); ITALY. Rome, San Giovanni, under Cupressus sempervirens , 28 November 2018, V. Migliozzi, MV281118-DSCN 3722 (GenBank accession MT416134 ); ITALY. Rome, under Cupressus sempervirens , 29 November 2019, A. Coppola and L. Nicoletti, MV 291119 LeuPil006 (GenBank accession MT416135 ); ITALY. Rome, under Cupressus sempervirens , 29 March 2021, V. Migliozzi, MVBB35, GenBank accession OM327662 (nrITS).

Discussion:—The types of Leucoagaricus aurantiovergens and L. pseudopilatianus var. roseodiffractus cluster together in a highly supported clade (MLB = 99%, BPP = 1), as shown in Fig. 1 . The nrITS sequences share 99% of sequence identity. Dimensions and morphology of spores, basidia and cheilocystidia observed in the isotypes L. aurantiovergens ((6.4–) 7.2– 7.7 –8.3 (–9.2) × 4– 4.4 –4.8 (–5.3) μm, Q= (1.4–) 1.6– 1.8 –1.9 (–2.1); 22–27 × 7–9 μm; 40–60 × 8–15 μm) and in the holotype L. pseudopilatianus var. roseodiffractus ((6.2–) 6.9– 7.6 –8.2 (–9) × (4.3) 4.5– 5 –5.4 (–6) μm, Q= (1.1–) 1.4– 1.5 –1.6 (–1.7); 24–27 × 7–8 μm; 40–50 × 9–12 μm) are extremely similar, and they fit with those reported in the original descriptions (Gennari & Migliozzi 1999; Migliozzi & Resta 2001). The types differ only in the diameter of the pileus covering terminal elements: in Leucoagaricus aurantiovergens they are wider ((10) 12–18 (20) μm, Gennari & Migliozzi 1999; 13–18 µm, new observations) than those of L. pseudopilatianus var. roseodiffractus (12 (13) µm, Migliozzi & Resta 2001; 10–12 µm, new observations). Combining morphological and molecular data, we reduce L. pseudopilatianus var. roseodiffractus to a synonym of L. aurantiovergens . In the same way, the recently described species L. paracupresseus can be considered a synonym of L. aurantiovergens , and although its basidiomes are smaller (21–35 mm diameter, Salom et al. 2021a, b) than those of L. aurantiovergens the two species are morphologically extremely similar and the nrITS sequences ( MZ230523 and OK235666 ) share a sequence similarity of 99%. Besides, the clade includes two sequences ( MT416134 , MT416135 ) deposited in GenBank as Leucoagaricus sp. from two collections morphologically examined in this study (MV281118-DSCN 3722, MV 291119 LeuPil006); the morphology and the molecular data identify these two collections as L. aurantiovergens . In the same group is the nrITS sequence of Leucoagaricus cf. cupresseus from France ( AY243627 ) ( Fig. 1 ). Leucoagaricus cupresseus was originally described as growing under Hesperocyparis macrocarpa (Cupressaceae) in California; then Boisselet & Guinberteau (2001) reported the occurrence of the same species in the Atlantic and Mediterranean coasts of France, also under Hesperocyparis macrocarpa . The doubts regarding the correct identification of the French specimen were reported by Vellinga (2010) in her work on the Lepiotaceous fungi in California. She observed that a French specimen ( AY243627 ) differed in the nrITS sequence from the Californian collections analyzed in her work, suggesting that L. pseudopilatianus and its varieties roseodiffractus and rugosoreticulatus might be very close or identical to the French collection (Vellinga 2010). The new molecular data obtained from the type of L. aurantiovergens show that the French specimen is not L. cupresseus , or L. paracupresseus as reported by Salom et al. (2021a, b), but instead a specimen of L. aurantiovergens (sequence identity 99% between AY243627 and OK235666 ).

Figures

FIGURE 1. Maximum Likelihood phylogram obtained from nrITS sequences of Leucoagaricus taxa. Cystolepiota seminuda was selected as outgroup taxon. Maximum Likelihood Bootstrap (MLB) values ≥ 70% (left) and Bayesian Posterior Probability (BPP) values ≥ 0.95 (right) are shown on the branches. Newly obtained sequences are reported in bold.

FIGURE 5. Leucoagaricus aurantiovergens. A. Basidiomes in the natural habitat coll. MVBB34; B. Basidiospores in Congo Red coll. MVBB34; C. Cheilocystidia coll. MVBB34; D. Cheilocystidia coll. PAD H0061557 (isotype L. aurantiovergens); E. Cheilocystidia coll. TR MV36/97 (holotype Leucoagaricus pseudopilatianus var. roseodiffractus); F. Pileus covering elements coll. MVBB34. Scale bars: A = 1 cm, B = 10 μm, C = 30 μm, D = 20 μm, E = 25 μm, F = 30 μm. Photos: A–C, F by Vincenzo Migliozzi; D–E by Niccolò Forin.

FIGURE 6. Leucoagaricus aurantiovergens coll.CAG P.12-9/8.39a. A–B. Basidiomes in the natural habitat; C. Basidiospores; D. Basidia; E. Cheilocystidia; F. Pileus covering elements. Scale bars: A–B = 2 cm, C–E = 10 μm, F = 50 μm. Photos by Alessia Tatti.